Princess Isabella of Valen has spent years studying medicine and developing a remedy for the plague. She returns to the capital quietly, hoping to offer it as a birthday gift to her father, King Arthur, who is about to remarry. Arthur's fiancée, Margaret, resents the princess for staying away and delaying the wedding. While riding through the capital, Margaret lets her carriage tear through the streets and nearly runs down commoners. Isabella stops her, only to be publicly humiliated and beaten by Margaret and her daughter, who accuse her of being a witch. The corrupt, fawning captain of the city guard helps them. Margaret burns the portrait of Isabella's mother and the precious herbs Isabella needs for her medicine, then orders her tied to a stake and burned alive. Just in time, King Arthur learns the truth and arrives with his guards in a fury.